It was fortunate all of the lions at Orana Wildlife Park were tucked up for the night in their secure house when last week's storm smashed the fence around the lion reserve.

Gale force winds brought down scores of trees across Canterbury and cut power to thousands of homes.

Several trees were toppled on the wildlife reserve on the western outskirts of Christchurch - including the large gum tree that flattened part of the fence - and meant the zoo had to run off limited generator power for the last 10 days.

Asked what would have happened if the tree had smashed the lion fence during daylight hours, Orana spokesman Nathan Hawke said the lions would have still been inside.

"After all of the natural disasters we've been through - heavy snow and earthquakes which have damaged fences - the lions are put away every night.

"In daytime hours where there are high winds, we also lock them away in their dens, and we've done that before.

"In the worst case scenario, where there was a hole in the fence and they escaped, our emergency procedures would kick in, but we're confident it would never get to that point."

The storm was the most damaging in the park's history, causing more damage than the earthquakes or large snow events of recent times.

"Many large trees came down causing damage to most fences," chief executive Lynn Anderson said.

"Luckily no animal houses or key buildings were severely damaged.

"Contractors and park staff have worked tirelessly since Wednesday morning to clear trees from fences, remove dangerous trees and tidy the debris."

Orana park was without mains power for seven full days, relying primarily on loaned generators which provided basic emergency infrastructure to enable staff to care for the animals.

Only a few animals developed 'cabin fever', Ms Anderson said, while back-up generators provided enough electricity for only the basics - minimal water supply, food storage and electric fencing systems.

"We directed our total limited generation capacity towards ensuring animal welfare needs were met to the best of our ability.

"I'm incredibly proud of our amazing team who've worked extremely hard in very trying conditions; an amazing amount has been achieved.

"All animals remain well and cared for and that's our most important duty," Ms Anderson said.

The park has been closed since last Tuesday, and after 10 days of storm clean-up, will officially re-open tomorrow (Saturday).

During the park's closure three animals died, including the "devastating" loss of popular 25-year-old giraffe, Nathalie who died on Tuesday night.

"She certainly was a very special grand old lady and we'll miss her dearly," Ms Anderson said.

Felicity, a 12-year-old kangaroo and Mavara, a 23-year-old zebra were also euthanised over the past few days due to "poor health".

Mr Hawke doubted the deaths were related to the storm. "They were all rather elderly animals, and we see it as a series of unfortunate events," he said.

The storm was the latest trying situation to test zoo staff.

A fortnight ago they were stunned when three water-shy gibbons escaped their enclosure by swimming across a moat.

Visitors were taken to safe, enclosed areas in the park.

"That was quite concerning but at the end of the day we obviously managed to get everybody safely back to the enclosure without too much trouble," said Rob Hall, Orana Park zoological manager.

"All necessary safety action was taken with the public - visitors and staff, so nobody was in any danger during that time."

Gibbons generally had a pleasant demeanour, Mr Hall said.

"They are generally okay. There was no stage at which the public felt concerned. We certainly had to get [people] into safe houses, so we moved the public to all our safe areas in the park as a precaution."

The gibbons were soon rounded up unharmed, but the zoo were forced to review the gibbons' accommodation set-up.